The invention relates to a cooling element provided with louvers to be used in a heat exchanger, particularly in a heat exchanger constructed so that the cooling element is under the influence of passing cooling medium, as air or water, used for cooling another medium flowing inside a circulating element and that the cooling element is used as a connecting member for two circulating elements.
A heat exchanger used in the automotive industry for cooling a motor in a vehicle may include a fin made of a corrugated strip. The corrugated strip itself is made of copper, copper-based alloy or aluminum or aluminum-based alloy and this corrugated strip is installed between circulating elements where medium to be cooled is circulated. The corrugated strip has a strong metallic bond made by a braze or a solder material with the circulating elements. One corrugated strip provides many cooling elements or fins between circulating elements. Further, the fins positioned between two circulating elements are installed substantially perpendicularly to the longitudinal direction of the fin. The fins may be cut between the two circulating elements to form a number of louvers twisted at an angle of 20-45° from the general plane of the fins. The louvers, which are provided for improving heat transfer capacity, are very small, from 0.75 to 1.5 mm, but the louvers are very efficient for the heat transfer capacity. The louvers are grouped together in different areas distributed along the direction of flow of the (outer) cooling medium. The louvers in a given area are twisted in one direction and the louvers in the or each adjacent area are twisted in the opposite direction.
When a cooling medium, such as air or water, is passing over the fins, the cooling medium is forced to follow a flow pattern defined by the louvers. At low cooling medium flow levels the flow has in spite of louvers space enough to pass directly between the fins. On the contrary, at moderate or high cooling medium flow levels the flow may be redirected several times and pass through the fins. This means more costs because of energy loss and this effect can be measured as a higher pressure drop over the heat exchanger.
The object of the present invention is to eliminate some drawbacks of the prior art and to achieve a cooling element to be used in a heat exchanger, particularly in a heat exchanger where the cooling element is a connecting member between two circulating elements.